Clock



FIG. 1 is a front elevational view of a clock showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left-side view thereof;

FIG. 4 is a right-side view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a clock, as shown and described. 